Once the majority accepts the fact that the asteroid will strike the Earth the deniers will claim that this will in fact boost the economy by creating jobs. But secretly they will be hoping the crisis will decimate developing nations and put the US back on top.

You have it exactly backwards. We do need a stock market and privately traded companies are subject to a lot less regulation regarding transparency then publicly traded ones. According to William Bernstein an efficient capital market is essential to economic growth.

I don't see what's brand new. What makes these recent shenanigans different from the ones that caused the stock market crash of 1929?

You're blaming the wrong market anyway. It's the credit markets that have run amok and caused this crisis. Unregulated, private trading in the credit market. Have a listen to this podcast.